Filling connections for fuel tanks are either formed in one piece with the filling tube or as separate members. Because of the difficulties arising in connection with the assembly of one-piece filling tubes the separate filling connections are usually preferred. The separate filling connection, if consisting of metal, is connected to the filling tube by welding or soldering or is connected to the filling tube via an elastic sleeve and with the aid of pipe clips or the like, especially when it is made of synthetic material. A one-piece filling connection has become known which is formed of synthetic material and is adapted to be fastened in the body opening by being snap positioned therein (German disclosure letter 2 553 881).
The "tank cap" which closes the filling connection on the outside is either designed as a bayonet type closure (which is the most widely spread type of embodiment) or is provided with an inner or outer thread and screwed onto the connection. In the case of the above mentioned known filling connection there is provided an outer sawtooth thread onto which the lid which is likewise formed of synthetic material may be screwed by means of a corresponding inner thread fitting into it. At annular seal is arranged on the inside of the thread of the lid and cooperates with the end face of the outer section of the connection. Another seal is arranged inside the thread of the connection and cooperates with the exterior lid inner surface.
In the case of the known filling connection there is no closure means provided for the lid. It is usually arranged inside the lid and with a bayonet closure is effective to cause an idle movement of the lid. In connection with a screw thread formation a predetermined axial position of the lid is necessary so that the bar of the closing device may be brought into the interlocking position. In both cases the adaptation of the axially effective sealing between the lid and a corresponding seating surface of the connection is predetermined right from the beginning and cannot be changed any more, so that in case of wear or fatigue a reduction of the sealing effect will occur with the result that fuel may escape.
The invention is based upon the problem of providing a filling connection for vehicles driven by internal combustion engines in which the lid may be interlocked in any position that may be desired independently of its axial position.
According to the invention this problem is solved in that the lid is provided with an axial hollow projection extending into the filling connection with a bar movably supported in said projection which is adapted to be adjusted transversely to the axis of the projection between an retracted and an extended position by means of a closure device arranged inside the projection, and in that there are arranged on the inside of the filling connection spaced from the opening thereof several circumferentially spaced elevations and/or deepenings with which the bar cooperates in the extended position thereof.
The filling connection which is preferably formed of synthetic material is provided on the inside thereof with circumferentially spaced elevations and/or deepenings spaced through a distance from the outer opening, which serve as arresting abutments for the bar of the closure device. If the lid is screwed onto the filling connection, the elevations or deepenings which have a length exceeding the width of the bar, make possible an interlocking engagement of the lid independently of the contact pressure force with which it is effective against the sealing. It is thus possible to screw the lid onto the connection with little contact pressure and with as great a contact pressure as may be desired and obtain an interlocking engagement in any of these positions and all the intermediate positions.
The corresponding abutments on the inside of the connection may have any shape that may be desired, all that has to be made sure is that they do not obstruct the introduction of a filling nozzle. Provision is made in one embodiment of the invention for the inside of the connection to be provided with a circumferentially extending toothing. The toothing in this case is preferably arranged at a position a short distance before the point where the filling connection is bent off in a direction towards the filling tube and becomes narrower in its cross sectional area. The invention does not make it a condition that the bar and toothing cooperate with each other without play. Provision is, however, made in one embodiment of the invention for the end of the bar to be shaped corresponding to the shape of the gap between adjacent teeth. In the interlocked position the bar is thus securely seated on the connection both axially and in the direction of rotation.
The closure device and the bar may again be designed in any suitable manner. Provision is made in one embodiment of the invention for this purpose for two diametrically arranged bar elements to be radially movably guided within the projection and through a radial opening provided in the projection. The bar elements are advantageously provided with an arcuate slot disposed in a radial plane, for the journal of the closure device which is movable on a circular path. Inside the projection there are provided suitable guide means for the bar elements. This guiding arrangement according to another embodiment of the invention may consist in that the wall of the projection pointing into the interior of the connection is provided with ribs on the inside thereof for guiding the bar elements.
The projection arranged axially at the lid is advantageously formed cylindrically or conically, with the latter shape being preferred. The inside of the filling connection is formed in correspondence with the manner in which the outside of the projection extends, so that the elevations or deepenings and toothings, respectively, are arranged on a circular or conical ring area. The projection is closed towards the filling pipe by means of a wall which, according to another embodiment of the invention, comprises the axially effective sealing cooperating with a radial seating area of the connection. In this manner, the sealing is displaced inside a considerable distance thereby obtaining a particularly good sealing effect. The position of the sealing, besides, prevents fuel from getting into contact with the closure device.
If the lid is formed of synthetic material, it is advantageous to form the projection separately as a cup-shaped member which is adapted to be connected to the inside of the lid by means of a suitable snap type connection.
For the retention of the closure device inside the projection provision is made in another embodiment of the invention for a cylindrical axial sleeve to be arranged inside the projection for the accommodation of a closure cylinder, said closure cylinder being provided with an elastic arresting projection getting snap positioned in a recess of the sleeve. The axial sleeve is preferably shaped in one piece with the lid.
One example of embodiment of the invention will be described in the following in more detail with the aid of drawings.